Polarization Axis Attenuation and Cross Polarization Resistant Antenna Orientation Assembly for Tracked Object

ABSTRACT

Methods and systems related to an antenna orientation are disclosed herein. In one specific embodiments, a system comprises a positioning device configured to generate a positioning signal, a control object, and an object antenna configured to receive the positioning signal. The object antenna has a first polarization axis and is located on the control object. The system also comprises a positioning device antenna configured to transmit the positioning signal. The positioning device antenna has a second polarization axis and is located on the positioning device. The first polarization axis and the second polarization axis are offset from parallel by greater than thirty degrees when the positioning device and control object are in a standard operating mode. The first polarization axis and the second polarization axis are offset from perpendicular by greater than thirty degrees when the positioning device and control object are in a standard operating mode.

BACKGROUND

Tracking an object in physical space can involve the transmission ofelectromagnetic signals and conducting analysis on those signals todetermine the physical position of the object. The analysis can involveTime of Arrival (TOA), Angle of Arrival (AOA), and/or Received SignalStrength Indication (RSSI) metrics. The signals can be referred to aspositioning signals because they are used to determine the position ofthe object. The signals can be generated by positioning devices. Theanalysis can involve the reception of many of such signals such as in amultilateration (MLAT) analysis. Tracking systems can be assisted by areflective tag or antenna located on the object that interacts with thepositioning signals. The positioning signals can be transmitted andreceived by antennas on the positioning devices. In certain approaches,an antenna on the object is also be used to transmit outboundpositioning signals which are generated on the object itself rather thanthe positioning devices.

SUMMARY

Methods and systems related to an antenna orientation are disclosedherein. In one specific embodiments, a system comprises a positioningdevice configured to generate a positioning signal, a control object,and an object antenna configured to receive the positioning signal. Theobject antenna has a first polarization axis and is located on thecontrol object. The system also comprises a positioning device antennaconfigured to transmit the positioning signal. The positioning deviceantenna has a second polarization axis and is located on the positioningdevice. The first polarization axis and the second polarization axis areoffset from parallel by greater than thirty degrees when the positioningdevice and control object are in a standard operating mode. The firstpolarization axis and the second polarization axis are offset fromperpendicular by greater than thirty degrees when the positioning deviceand control object are in a standard operating mode.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 illustrates a system for tracking the position of a pointingobject using a set of positioning devices that transmit and receivesignals to and from an antenna located on the pointing object inaccordance with specific embodiments of the present invention.

FIG. 2 illustrates an antenna radiation pattern showing polarizationaxis attenuation and an example of cross polarization in accordance withthe related art.

FIG. 3 illustrates two sets of a cross sections for a pointing objectand a positioning device which reveal antenna assemblies located withinthe devices that are in accordance with specific embodiments of thepresent invention.

FIG. 4 illustrates a set of cross sections for a pointing object and apositioning device which reveal antenna assemblies located within thedevices that are in accordance with specific embodiments of the presentinvention.

DETAILED DESCRIPTION

Systems and methods used for improving the performance of an antenna ina positioning system are disclosed in detail herein below. The systemscan involve antenna assemblies for properly fixing the antenna relativeto the position of the device to which it is attached. The methods caninvolve tilting the antenna relative to a main axis of the device. Theantennas can be located in a positioning device in the positioningsystem or in the tracked object. The main axis of the device can bedefined relative to the orientation that the device will generally beplaced in during its standard operating mode. For example, the main axisof a remote control is defined by the pointing axis of the remotecontrol. As another example, the main axis of a wall-mounted positioningdevice is defined by a vector extending from the center of the deviceupwards towards the ceiling and parallel to the wall. The antenna can bepositioned to optimize the performance of a tracking system used totrack the object. Specifically, the angle at which the antenna is tiltedby an antenna assembly can be selected to optimize the performance of atracking system used to track the object. Specific embodiments andvariations of these concepts are disclosed below with reference to FIGS.1-4. The specific embodiments of these concepts as disclosed in thissection are provided for explanatory purposes and are not meant to limitthe invention, the scope of which is provided by the appended claims.

Specific embodiments of the invention relate to the positioning of anantenna in a positioning device or an object to be tracked by apositioning system relative to the body of the device itself. Specificembodiments of the invention relate to the relative positioning of anantenna in a positioning device and an antenna in an object to betracked by a positioning system. A positioning system 100 is providedwith reference to FIG. 1. Positioning system 100 includes a set ofpositioning devices 110, an object to be tracked 120, and an optionalserver 130. The object to be tracked can be a mobile device. The set ofpositioning devices can transmit and receive positioning signals 111that are reflected off, or transmitted by, object 120. While positioningsignals are exchanged between the object and the positioning devices,the analysis of the signals conducted to determine a position of theobject can be conducted on the object, by the set of positioningdevices, on the server, or any combination thereof.

The object being tracked can be any object whose position needs to bedetermined by an automated system. The object can be a control objectsuch as a device for generating control signals. The object can be apointing object such as a remote control, presentation pointer,inventory management device, or a toy used for wireless tag. Thepointing object will have a defined pointing direction which isassociated with a pointing axis the user aligns a target with whenpointing. The pointing object could be configured to transmit signalsalong the pointing axis in order to fulfill its main functionality. Inthe illustrated situation, the pointing object is a remote control, thetarget is a television, and the signal includes a power-on command forthe television. In other embodiments, the object can be a drone, smartphone, tablet computer, wearable computing device, or any othercomputing device.

In the specific example of FIG. 1, object 120 is a dedicated device thatoperates as a remote control and the pointing axis 113 is the pointingdirection of the remote control. The remote can operate to control oneor more electronic devices and may transmit signals to these devicesusing any form of wireless transmitter. The tracking system can be usedto determine which device the controller is pointing towards at anygiven time. Specifically, the positioning system can be used todetermine the direction of the pointing axis in a reference frame usedto identify what the target of the pointing object might be. In theillustrated case, user 101 can align pointing axis 113 with target 102to provide a command to the television. As will be described below, thesame antenna could be used to send the command, or other signaltransmitted by the pointing object, and interact with the positioningsignals from the positioning devices 110.

A set of external positioning devices for tracking the position of anobject in accordance with this disclosure can take on various forms. Theset of external positioning devices can include two or moresubstantially homogenous elements that measure the position of theobject in physical space. The set of external positioning devices canmeasure the position of the object using wireless signals. For example,the external positioning devices can direct wireless signals towards atag or transceiver on the object and conduct a TOF analysis on thosesignals and obtain a measurement of the object's position using MLAT.The external positioning device can include a separate wirelesstransmitter for communicating encoded information with the otherexternal positioning devices and the object such as via a Wi-Fi, Z-wave,or Zigbee protocol.

In the specific system illustration of FIG. 1, the set of externalpositioning devices 110 are a set of wall-mounted anchors located in aroom with object 120. Object 120 can also include a distance sensor andlocal positioning system (LPS) receiver for communicating with the setof external positioning devices 110 and determining the position ofobject 120. In the illustrated case, the external positioning devicestransmit wireless signals at an antenna 121 on the device and obtain ameasurement of its position using TOF and MLAT. Antenna 121 can be anLPS receiver designed to interact with the set of external positioningdevices 110. The set of external positioning devices 110 may be arrangedin a space such that they are not co-linear. The set of externalpositioning devices 110 may function better if they have a line-of-sightto one another. Accordingly, the set of external positioning devices 110can be mounted high (e.g. at least 2 meters above the floor). Theexternal positioning devices can be mounted to different walls of thespace. The LPS receiver may implement an ultra-wideband (UWB) localpositioning system. The external positioning devices may communicatewirelessly with one another and with the object 110 to implement a UWBLPS system or any other LPS system known in the art. In particular, thepositioning devices can include antennas such as antenna 111 to transmitand receive positioning signals. The set of antennas and set ofpositioning devices can have a one-to-one correspondence. An antenna121, located on the object, can be referred to as an object antenna. Anantenna 111, located on a positioning device, can be referred to as apositioning device antenna to distinguish the two antennas. Inembodiments where the object is a pointing object, the antenna can bereferred to as a pointing object antenna.

The object and positioning antennas can take on various forms. Asillustrated, object antenna 121 and positioning device antenna 111 areUWB omnidirectional and linear polarization (OLP) antennas. In alinearly polarized antenna, the polarization axis is generally theantenna's axis of greatest length. In FIG. 1, object antenna 121 has afirst polarization axis 122 and positioning device antenna 111 has asecond polarization axis 112. The antennas can be fixed on thepositioning device and object with a relative offset of these first andsecond axes to improve the performance of the positioning system as willbe described below. The relative offset can be measured when each of thedevices are positioned in their standard operating position. While theantennas of the other positioning devices besides 3 are not shown, eachof the devices can have an antenna that is fixed in the same mannerrelative to the body of the positioning device and each antenna canshare the polarization axis 112. Although FIG. 1 illustrates eachantenna as being an omnidirectional patch antenna, the antennas can: bedirectional antennas; have patch, dual patch, dipole, monopole, slot, orsplit ring resonator antenna structures; and can have linearpolarization, circulator polarization, or elliptical polarization.

FIG. 2 includes two diagrams that illustrate relevant behaviors ofwireless systems for purposes of explaining the benefits of some of theembodiments disclosed herein. The disclosure are in accordance with therelated art. The wireless systems in accordance with FIG. 2 are bothomnidirectional and linearly polarized. However, the disclosures hereinare more broadly applicable and these examples are provided merely forillustrating benefits associated with a specific subset of theembodiments disclosed herein.

Diagram 200 shows a radiation pattern 202 of object 120 from FIG. 1.Radiation pattern 202 is drawn relative to an ideal omnidirectionalradiation pattern in the form of a perfect sphere shown by twoconcentric circles 201 that have been rotated relative to each otheraround the polarization axis of the antenna 122. As seen, the radiationpattern includes an attenuation 203 along the polarization axis of theantenna 122. The radiation pattern 202 can be approximated by a torus,with the polarization axis as its center. This implies a strongattenuation of transmissions and receptions in the direction ofpolarization axis 122. Theoretically, reception and transmission is nullon axis 122 though in real situations there is still some signalreception and transmission it is just significantly attenuated.

Diagram 210 illustrates two linearly polarized electromagnetic waves 211and 212 where wave 211 has a horizontal polarization and wave 212 has avertical polarization. Wave 211 is generated by a patch antenna with ahorizontal polarization axis 213. Wave 212 is generated by a patchantenna with a vertical polarization axis 214. As the polarization of asignal is rotated from the polarization of wave 211 to the polarizationof wave 212, patch antenna 213 will have an increasingly challengingtime resolving the signal. The same is true for antenna 214 as thepolarization of wave 212 is rotated towards that of wave 211. In thecase of antenna 213 attempting to communicate with antenna 214 (i.e.,two antennas communicating with orthogonal polarizations) communicationis theoretically impossible. This phenomenon is called crosspolarization.

In specific embodiments, the antenna on the positioning device and theantenna on the object being tracked can be oriented to maximize theefficacy of communication between the two devices. The positioningantenna polarization axis and the object antenna polarization axis canbe offset from parallel by greater than thirty degrees, and offset fromperpendicular by greater than thirty degrees. In more specificembodiments, the positioning antenna polarization axis and the objectantenna polarization axis can be offset from each other by forty-fivedegrees. In the case of linearly polarized antennas, the benefit of suchan approach is that the effects of on-axis attenuation and crosspolarization are both minimized to an appreciable degree. The benefitsof this approach have been observed to apply mainly within a fifteendegree plus or minus variation from a forty-five degree offset. Theantennas can be fixed relative to the position of the positioning deviceand object to meet these conditions while the devices are placed intheir standard operating positions. The antennas can be fixed in suchmanner by antenna assemblies that are encapsulated within the devices.The antenna assemblies can include a substrate, such as a printedcircuit board, to which the antennas are connected. The antennas can beheld at an angle off the substrate and the substrate can have a fixedconfiguration relative to the device by being permanently fixed to aframe or body of the device. The antennas can also be positioned at anangle off from a main axes of the device while being flush with thesubstrate. In other words, the antennas can either be tiled by beingrotated in the plane of the substrate or by being rotated out of theplane of the substrate.

FIG. 3 can be used to describe a set of specific embodiments of theinvention that are in accordance with the approach described in theprevious paragraph. In diagram 310 an object 311 with a pointing axis312 includes a body 313. Object 311 is a pointing object whose pointingaxis is generally held horizontal during the standard operating mode ofthe devices. For example, object 311 could be a remote control. Aportion of body 313 has been removed in the figure to illustrate aprinted circuit board 314 on which an antenna 315 has been fixed. Theprinted circuit board 314 also includes a microprocessor. Themicroprocessor can be communicatively coupled to antenna 315 via theprinted circuit board 314. The microprocessor can store instructions togenerate or process positioning signals received by antenna 315. Themicroprocessor can also generate and transmit commands to devices thatare identified by the user of the pointing object. As illustrated, themicroprocessor, the antenna, and the antenna assembly are allencapsulated within the body of the device.

Diagram 310 also includes positioning device 317 which includes a body318 that has been partially removed in the figure to reveal a printedcircuit board 319. The printed circuit board 319 also includes amicroprocessor. In the illustrated case, the positioning device antenna320 is aligned flush with printed circuit board 319. Antennas 320 and315 can both be OLP antennas such that the polarization axis 32 ofantenna 320 is parallel with the surface of the wall to whichpositioning device 317 is mounted. The microprocessor can becommunicatively connected to the positioning device antenna 320 via theprinted circuit board 319. The microprocessor can store instructions togenerate or process positioning signals received by antenna 320. Asillustrated, the microprocessor, the antenna, and the antenna assemblyare all encapsulated within the body of the device.

Both antennas 315 and 320 can be fixed in place by an antenna assembly.The antenna assembly can include a socket on a printed circuit board.For example, if the antennas were patch antennas with female coaxialsockets, the antenna assembly could include a male coaxial socketintegrated with the printed circuit board. In the case of object 311,the antenna assembly can hold the antenna at an angle off the surface ofthe printed circuit board. The angle can be held by a socket formed onthe printed circuit board and compatible with the antenna. For example,the socket can be an angled coaxial connection formed on the surface ofthe printed circuit board. The angle can be set to hold the polarizationaxis of the antenna at an orientation that is greater than thirtydegrees from parallel with the pointing axis and less than sixty degreesfrom perpendicular with the pointing axis. In specific embodiments, theangle can be set to hold the polarization axis of the antenna atforty-five-degree angle offset from the pointing axis. In an alternativeembodiment, the antenna can be kept flush with the substrate whilehaving its polarization axis rotated out of alignment with pointingdirection 312. The same angles applied for antenna 315 can be appliedfor such an approach.

Positioning the pointing objects antenna's polarization axis 316 at theangles described in the previous paragraph provides certain benefitsbecause doing so indirectly assures that the polarization axis of thepointing object is set to a desired angle offset from the polarizationaxis of the positioning devices's antenna while each device is in itsstandard operating mode. The detailed view of antenna 315 in diagram 310includes a labeled angle theta-sub-one defined by the offset of thepointing axis 312 from the polarization axis of the pointing object'santenna 316. As illustrated, the polarization axis 321 of antenna 320can be parallel with the surface of the wall to which positioning device317 is mounted. As such, perfect cross polarization between the twoantennas would occur when theta-sub-one was set to zero orone-hundred-eighty. Likewise, perfect along polarization axisattenuation would occur when theta-sub-one was set to ninety ortwo-hundred-seventy. Minimizing both sources of attenuation cantherefore be achieved by placing theta-sub-one somewhere on the order ofthirty to sixty degrees, such as at forty-five degrees. Those ofordinary skill in the art will recognize that similar windows in theother three quadrants of the unit circle would provide similar benefits(i.e., those in which theta-sub-one was approximatelyone-hundred-thirty-five, two-hundred-twenty-five, andthree-hundred-fifteen degrees). Pointing axis 312 therefore serves as aproxy for a perpendicular axis to the polarization axis of antenna 320and configuring antenna 315 at an angle off the pointing directionindirectly assures a desired offset between the pointing object antennaand the positioning device antenna.

Diagram 310 is similar to diagram 300 except that the antenna 330 ofpositioning device 317 has been tilted out from being parallel with thewall and the antenna 325 of the pointing object 311 has been set to havea polarization axis equal to the pointing axis 312 of the pointingobject. In specific embodiments in accordance with diagram 310, theantenna assembly is configured to assure that the polarization axis ofthe positioning device's antenna is greater than thirty degrees offsetfrom being perpendicular to the wall and greater than thirty degreesoffset from being parallel to the wall. Those of ordinary skill in theart will recognize that the tilting of antenna 330 is just one of manytilting directions that could achieve this result. In an alternativeembodiment, the polarization axis of antenna 330 can be kept parallelwith the wall, as in the case of diagram 300, while being rotatedsideways along the wall in either a clockwise or counterclockwisedirection. The same angle offsets applied for antenna 315 can be appliedfor such an approach, but with reference to the main axis of positioningdevice 317. In this example, the main axis of positioning device 317points directly up from the center of the positioning device andparallel to the wall.

The remaining aspects of diagram 310 match those of diagram 300. Inparticular, both antenna 330 and 325 are LP antennas. As a result, thepolarization axis of the pointing object antenna 325 is offset from thepolarization axis 326 of the positioning device antenna 330 by an angletheta-sub-two. The angle can be set similarly to theta-sub-one.Specifically, the angle can be set to somewhere between thirty and sixtydegrees, such as forty-five degrees. Those of ordinary skill in the artwill recognize that similar windows in the other three quadrants of theunit circle would provide similar benefits (i.e., those in whichtheta-sub-one was approximately one-hundred-thirty-five,two-hundred-twenty-five, and three-hundred-fifteen degrees). Inaccordance with this configuration, the cross polarization andalong-axis attenuation between the two antennas is minimized just as inthe example of diagram 300. In accordance with either physicalconfiguration of the devices in diagram 300 and 310, when the devicesare in their standard operating configurations, the polarization axis ofthe pointing object and the polarization axis of the positioning devicesare offset from parallel by greater than thirty degrees, and are offsetfrom perpendicular by greater than thirty degrees.

The examples in FIG. 3 illustrate a single positioning device. However,positioning devices 317 and 327 can be individual positioning devices ina set of positioning devices. The multiple devices can be installed andbe placed on different walls or on the same wall. The devices can begenerally placed at the same height. In these embodiments, thepolarization axes of the antennas in the various positioning devices canall be identical and recognize the benefits disclosed herein. However,the axes of each device can also be distributed to account for the factthat the tracked object will tend to be oriented with slight variationsaround its standard operating position. For example, in a positioningsystem with three or four positioning device and a remote control havean antenna with a polarization axis that is aligned with its pointingdirection, the polarization of the antennas can be distributed evenlyfrom thirty degrees to sixty degrees offset from parallel with thesurface of the wall.

FIG. 4 provides an illustration of another potential configuration forthe antenna on a pointing object and on a wall-mounted positioningdevice that are in accordance with specific embodiments of the disclosedinvention. Wall-mounted positioning device 400 is shown with its mainaxes 401 pointing up towards the ceiling of the room and parallel withthe wall to which device 400 is mounted. As illustrated, an LP patchantenna 403 has been positioned within device 400 such that itspolarization axis 403 is at an angle theta-sub-three offset from themain axes 401. The view of positioning device 400 is a view lookingdirectly at the wall as opposed to the side view of FIG. 3. At the sametime, an LP patch antenna 411 on pointing device 410 has been positionedsuch that its polarization axis 412 is in line with the pointingdirection of pointing object 410. The view of pointing object 410 inFIG. 4 is a top down view of the object as opposed to the side view ofFIG. 3. The angle theta-sub-three offset can take on the samecharacteristics as the angle theta-sub-two and theta-sub-one mentionedabove in order to provide those same benefits. Specifically,theta-sub-three can be beneficially placed from thirty to sixty degrees.In a specific embodiment, theta-sub-three, can be forty-five degrees ina more specific embodiment. Since, in the standard operating mode,pointing axis 412 will be perpendicular to main axes 401, iftheta-sub-three is selected to be from thirty to sixty degrees, theangle between the polarization axes of the two devices will likewise befrom sixty to thirty degrees respectively. As such, the combined systemwill recognize some of the benefits disclosed herein.

While the specification has been described in detail with respect tospecific embodiments of the invention, it will be appreciated that thoseskilled in the art, upon attaining an understanding of the foregoing,may readily conceive of alterations to, variations of, and equivalentsto these embodiments. For example, the disclosure used the example of awall-mounted positioning devices and a pointing object that is mostoften positioned parallel with a floor to illustrate benefits of some ofthe disclosed embodiments. However, specific embodiments disclosedherein are more broadly applicable to any combination of positioning andpointing objects where the devices have a fixed orientation relative toeach other in a standard operating mode. Furthermore, as manypositioning devices include internal gyroscopes or other sensors usedfor determining an orientation of the positioning device, theorientation of the antenna can be a configurable property of thepointing object and the relative orientation of the positioning deviceantenna to the pointing object antenna can be controlled by a feedbackloop which evaluates data from such sensors and adjusts the orientationof either antenna in response to that data. Such a feedback loop couldbe computer-controlled or wholly mechanical. The target of the feedbackloop could be set to maintain the polarization axis of the device towithin a forty-five degree offset plus or minus fifteen degrees from thepolarization axis of the counterpart device. Furthermore, though manyexamples in the disclosure were directed to positioning devices, thesame approaches could be applied to any secondary device, or set ofsecondary devices that are meant to transmit signals to an antenna on amobile object. The signals can include any type of command or data. Thesecondary devices could share any of the general characteristicsmentioned above with respect to the positioning devices. For example,the secondary devices could be wall mounted and could have a one-to-onecorrespondence with a set of OLP antennas. The set of OLP antennas couldbe tilted as described above with reference to the antennas on thepositioning devices. These and other modifications and variations to thepresent invention may be practiced by those skilled in the art, withoutdeparting from the scope of the present invention, which is moreparticularly set forth in the appended claims.

What is claimed is:
 1. A system comprising: a positioning deviceconfigured to generate a positioning signal; a control object; an objectantenna configured to receive the positioning signal, having a firstpolarization axis, and located on the control object; a positioningdevice antenna configured to transmit the positioning signal, having asecond polarization axis, and located on the positioning device; whereinthe first polarization axis and the second polarization axis are offsetfrom parallel by greater than thirty degrees when the positioning deviceand control object are in a standard operating mode; and wherein thefirst polarization axis and the second polarization axis are offset fromperpendicular by greater than thirty degrees when the positioning deviceand control object are in a standard operating mode.
 2. The system ofclaim 1, wherein: the positioning signal is an ultra-wide bandpositioning signal; and the object antenna and positioning deviceantenna are both omnidirectional and linear polarization antennas. 3.The system of claim 2, wherein: the control object is a remote control;the remote control has a pointing axis; and the object antenna is tiltedon the control object to offset the pointing axis from the firstpolarization axis by greater than thirty degrees and less than sixtydegrees.
 4. The system of claim 1, further comprising: a microprocessoron the positioning device storing instructions to generate thepositioning signal; a printed circuit board on the positioning device;wherein the microprocessor is located on the printed circuit board;wherein the microprocessor is communicatively connected to thepositioning device antenna via the printed circuit board; and whereinthe positioning device antenna is an omnidirectional and linearpolarization antenna.
 5. The system of claim 4, further comprising: anantenna assembly that fixes the positioning device antenna at an angleoffset relative to the printed circuit board; wherein the angle isgreater than thirty degrees and less than sixty degrees; and wherein thepositioning device antenna, the antenna assembly, and the printedcircuit board are all encapsulated within the positioning device.
 6. Thesystem of claim 1, wherein: the positioning device is mounted to a wall;the second polarization axis is greater than thirty degrees offset frombeing perpendicular to the wall; the second polarization axis is greaterthan thirty degrees offset from being parallel to the wall; the controlobject is a remote control; the remote control has a pointing axis; andthe positioning signal is used to determine the pointing axis.
 7. Thesystem of claim 1, further comprising: a set of positioning devices thattransmit a set of positioning signals to the control object and includethe positioning device; a set of positioning device antennas located onthe set of positioning devices in a one-to-one correspondence with theset of positioning devices and include the positioning device antenna;and wherein the set of positioning device antennas share the secondpolarization axis.
 8. The system of claim 1, wherein: wherein the firstpolarization axis and the second polarization axis are offset from eachother by forty-five degrees.
 9. The system of claim 1, wherein: thecontrol object is a pointing device; the pointing device has a pointingaxis; and the pointing axis is aligned with the first polarization axis.10. The system of claim 1, further comprising: a set of wall-mountedsecondary devices; a set of OLP secondary device antennas: (i) locatedon the set of wall-mounted secondary devices in a one-to-onecorrespondence; (ii) having a secondary device antenna polarization axisand (iii) tilted to set the secondary device antenna polarization axisgreater than thirty and less than sixty degrees offset from horizontal;wherein the positioning signal is in a set of positioning signals; andwherein the set of OLP secondary device antennas transmit the set ofpositioning signals to the control object.
 11. The system of claim 10,wherein: the set of positioning signals is a set of UWB positioningsignals; and the system is a UWB positioning system.